A Catholic priest is among those being held by the extremists in the southern city of Marawi

Filipino authorities have reached out to parties who may be able to talk with Muslim militants in a bid to secure the freedom of hostages in a southern city where a week of fighting has killed 129 people, officials said on Wednesday.

Troops have cleared almost 90 per cent of Marawi city, where the gunmen linked to ISIS have been fending off government troops since a botched raid to capture a veteran rebel leader triggered a militant siege, said military spokesman Brig Gen Restituto Padilla. He said that militant leader Isnilon Hapilon is believed to be still in Marawi.

Padilla said 960 civilians have been rescued, and an estimated 1,000 residents remain trapped in the city. The dead include 89 militants, 19 civilians and 21 government forces, Padilla said.

A video of a Catholic priest taken hostage is being assessed by experts, he added. He said the video seems authentic, but Fr Teresito Suganob appeared to be speaking under duress and militants are apparently using the video for propaganda.

In the video, Fr Suganob said he is being held alongside 200 other captives, including children, in what appeared to be a battle-scarred part of Marawi.

“We want to live another day, we want to live another month,” Fr Suganob said, standing in front of debris and partially burned buildings. Directing his remarks to Philippine President Rodrigo Duterte, he said: “We want to live few years and in your generosity, Mr President, in your heart, we know you can make something (happen).”

An evacuated child is carried by a Filipino soldier in Marawi (AFP/Getty Images)

Marawi Bishop Edwin de la Pena confirmed that it was Fr Suganob in the video.

Padilla said there have been efforts to reach out to parties who may conduct back channel talks to help free the hostages. He assured the captives’ families that the military is doing its best to keep them safe. He did not elaborate.

Padilla said the video indicates the extremists are fighting for survival.

“They are trapped, they are contained,” he said. “They are in areas that they will never come out alive unless they surrender.”

Duterte, who declared martial law in Mindanao, has approved the creation of a “peace corridor” to hasten the rescue of civilians and delivery of humanitarian aid for displaced persons, said presidential spokesman Ernesto Abella.

He said the corridor will be implemented by the government and the main separatist group, the Moro Islamic Liberation Front, which has signed a peace agreement in exchange for Muslim autonomy in Mindanao, the southern third of the Philippines where a Muslim rebellion has raged for decades.

Hapilon, the militant leader wanted by the US for his alleged involvement in kidnappings and bomb attacks that also targeted Americans in the Philippines, is still believed to be in Marawi.

“We believe he is still there, and we believe that is why they are putting up a very stiff resistance in the areas that they are still being held up and being cleared,” Padilla told reporters in Manila, the capital.